RE: question on "forest-like anonymous individuals" restriction of OWL 2 DL

Hello,

Yes, you are right.

Boris

> -----Original Message-----
> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-request@w3.org] On
> Behalf Of Michael Schneider
> Sent: 28 June 2009 22:52
> To: Ian Horrocks
> Cc: OWL 1.1; Boris Motik
> Subject: RE: question on "forest-like anonymous individuals" restriction of
> OWL 2 DL
> 
> Hi Ian!
> 
> Yes, I got confused: The restrictions do not take inferred statements into
> account.
> 
> Also, from what you say below I now see that even "diamond-shaped"
> structures are disallowed in OWL 2 DL, e.g.
> 
>   _:x ex:p _:y .
>   _:x ex:q _:y .
> 
> And since only syntax counts, it wouldn't even help to have another axiom
> stating
> 
>   ex:p owl:equivalentClass ex:q .
> 
> right?
> 
> Cheers,
> Michael
> 
> >-----Original Message-----
> >From: Ian Horrocks [mailto:ian.horrocks@comlab.ox.ac.uk]
> >Sent: Sunday, June 28, 2009 12:12 AM
> >To: Michael Schneider
> >Cc: OWL 1.1; Boris Motik
> >Subject: Re: question on "forest-like anonymous individuals" restriction
> >of OWL 2 DL
> >
> >I think that the confusion arises from the fact that the forest in
> >question is not defined by the ontology assertions. The point is that
> >in order for the ontology to be in OWL 2 DL it must be possible to
> >arrange the anonymous individuals in a forest such that the three
> >conditions (which *do* refer to ontology assertions) are satisfied.
> >In the case of the second example, it is easy to see that there can
> >be no such forest satisfying both the first and second conditions,
> >namely:
> >
> >"for each assertion in Ax of the form ObjectPropertyAssertion( OPE
> >_:x _:y ), either _:x is a child of _:y or _:y is a child of _:x in F"
> >
> >and
> >
> >"for each pair of anonymous individuals _:x and _:y such that _:y is
> >a child of _:x in F, the set Ax contains at most one assertion of the
> >form ObjectPropertyAssertion( OPE _:x _:y ) or ObjectPropertyAssertion
> >( OPE _:y _:x )".
> >
> >In fact the purpose of adding the second example was to emphasise
> >that not only cycles, but any non-tree like arrangement of anonymous
> >individuals is illegal in OWL 2 DL.
> >
> >Regards,
> >Ian
> >
> >
> >On 27 Jun 2009, at 01:01, Boris Motik wrote:
> >
> >> Hello,
> >>
> >> No, not really: since OWL 2 has inverse roles, the actual
> >> directionality of the
> >> property assertions doesn't matter. That is, the role assertion
> >>
> >> ObjectPropertyAssertion( a:hasDaughter _:b1 _:b2 )
> >>
> >> is equivalent to
> >>
> >> ObjectPropertyAssertion( InverseObjectProperty(a:hasDaughter) _:b2
> >> _:b1 )
> >>
> >> Now if the latter is circular, the former should be circular as
> >> well, given that
> >> the two assertions are semantically equivalent.
> >>
> >> Regards,
> >>
> >> 	Boris
> >>
> >>> -----Original Message-----
> >>> From: Michael Schneider [mailto:schneid@fzi.de]
> >>> Sent: 27 June 2009 01:52
> >>> To: Boris Motik
> >>> Cc: OWL 1.1
> >>> Subject: RE: question on "forest-like anonymous individuals"
> >>> restriction of
> >>> OWL 2 DL
> >>>
> >>> Hi Boris!
> >>>
> >>> The second counter example states
> >>>
> >>>   ObjectPropertyAssertion( a:hasChild _:b1 _:b2 )
> >>>   ObjectPropertyAssertion( a:hasDaughter _:b1 _:b2 )
> >>>
> >>> But shouldn't it be
> >>>
> >>>   ObjectPropertyAssertion( a:hasChild _:b1 _:b2 )
> >>>   ObjectPropertyAssertion( a:hasDaughter _:b2 _:b1 )
> >>>                                          ^^^^^^^^^
> >>>
> >>> in order to build a circular structure?
> >>>
> >>> Cheers,
> >>> Michael
> >>>
> >>>> -----Original Message-----
> >>>> From: Boris Motik [mailto:boris.motik@comlab.ox.ac.uk]
> >>>> Sent: Friday, June 26, 2009 1:29 PM
> >>>> To: Michael Schneider; 'OWL 1.1'
> >>>> Subject: RE: question on "forest-like anonymous individuals"
> >>>> restriction
> >>>> of OWL 2 DL
> >>>>
> >>>> Hello,
> >>>>
> >>>> In response to Michael's comment, Ian and I have made the following
> >>>> changes to
> >>>> the Syntax document:
> >>>>
> >>>> http://www.w3.org/2007/OWL/wiki/index.php?
> >>>> title=Syntax&diff=24654&oldid=
> >>>> 24647
> >>>>
> >>>> I hope things are clearer now. Please let me know should you have
> >>>> any
> >>>> comments.
> >>>>
> >>>> Regards,
> >>>>
> >>>> 	Boris
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: public-owl-wg-request@w3.org [mailto:public-owl-wg-
> >>>> request@w3.org] On
> >>>>> Behalf Of Michael Schneider
> >>>>> Sent: 29 May 2009 20:46
> >>>>> To: OWL 1.1
> >>>>> Subject: question on "forest-like anonymous individuals"
> >>>>> restriction
> >>>> of OWL 2
> >>>>> DL
> >>>>>
> >>>>> Hi all!
> >>>>>
> >>>>> I had to explain to someone the "forest-like anonymous individuals"
> >>>>> restriction of OWL 2 DL (Section 11.2 of the Structural Spec),
> >>>>> but I
> >>>> found
> >>>>> myself uncertain about it. In particular, I'm unclear how
> >>>>> "fixed" the
> >>>> variable
> >>>>> "OPE" is in the set of conditions.
> >>>>>
> >>>>> But it's easier to show my problem by an example: It's clear to me
> >>>> (also from
> >>>>> the example following the formal definition) that the following is
> >>>> /not/
> >>>>> allowed in OWL 2 DL:
> >>>>>
> >>>>>   _:x :p _:y
> >>>>>   _:y :p _:x
> >>>>>
> >>>>> But what about
> >>>>>
> >>>>>   _:x :p _:y
> >>>>>   _:y :q _:x
> >>>>>
> >>>>> with /different/ properties?
> >>>>>
> >>>>> Michael
> >>>>>
> >>>>> --
> >>>>> Dipl.-Inform. Michael Schneider
> >>>>> Research Scientist, Dept. Information Process Engineering (IPE)
> >>>>> Tel  : +49-721-9654-726
> >>>>> Fax  : +49-721-9654-727
> >>>>> Email: michael.schneider@fzi.de
> >>>>> WWW  : http://www.fzi.de/michael.schneider
> >>>>>
> >>>> ====================================================================
> >>>> ===
> >>>>> FZI Forschungszentrum Informatik an der Universität Karlsruhe
> >>>>> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe
> >>>>> Tel.: +49-721-9654-0, Fax: +49-721-9654-959
> >>>>> Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe
> >>>>> Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael
> >>>> Flor,
> >>>>> Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer
> >>>>> Vorsitzender des Kuratoriums: Ministerialdirigent Günther
> >>>>> Leßnerkraus
> >>>>>
> >>>> ====================================================================
> >>>> ===
> >>>>>
> >>>>
> >>>
> >>> --
> >>> Dipl.-Inform. Michael Schneider
> >>> Research Scientist, Dept. Information Process Engineering (IPE)
> >>> Tel  : +49-721-9654-726
> >>> Fax  : +49-721-9654-727
> >>> Email: michael.schneider@fzi.de
> >>> WWW  : http://www.fzi.de/michael.schneider
> >>> =====================================================================
> >>> ==
> >>> FZI Forschungszentrum Informatik an der Universität Karlsruhe
> >>> Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe
> >>> Tel.: +49-721-9654-0, Fax: +49-721-9654-959
> >>> Stiftung des bürgerlichen Rechts, Az 14-0563.1, RP Karlsruhe
> >>> Vorstand: Prof. Dr.-Ing. Rüdiger Dillmann, Dipl. Wi.-Ing. Michael
> >>> Flor,
> >>> Prof. Dr. Dr. h.c. Wolffried Stucky, Prof. Dr. Rudi Studer
> >>> Vorsitzender des Kuratoriums: Ministerialdirigent Günther Leßnerkraus
> >>> =====================================================================
> >>> ==
> >>
> >>
> >>

Received on Sunday, 28 June 2009 20:55:26 UTC